1. Field of the Invention
This invention relates to the process, apparatus and system for weighing moving objects preferably individual freight cars of different dimensions in a train comprising a plurality of such freight cars.
2. Background of Prior Art
The weighing of moving loads such as railway rolling stock, particularly freight cars, locomotives and trucks is a well-established technology. U.S. Pat. No. 2,543,794 entitled, "Track Scale" issued on Mar. 6, 1951 on an application filed Nov. 19, 1945 carries an excellent and detailed historical description of the technology and objectives of this art. As early as that date, it was known to use heavy duty track scales to weigh cars in motion utilizing a weight scale beam coupled with automatic weight recording devices capable of automatically printing out the weight on the weight tickets.
At that time and continuing up to the present time a key technique of delineating the length of the particular car or truck was based on the spacing of the car axles supporting the truck. The presence of a car axle was determined by various trips or trip mechanisms, such as mechanical switches and photo electric devices and other "position-responsive devices".
Early in the development of the art it was recognized that the force exerted by adjacent cars in a moving train would adversely effect the accuracy of the weight. Therefore slopes were built into both the approaches and exits of track scales and various mechanical coupling systems were devised to facilitate decoupling at critical juncture in the ascertainment of weight. U.S. Pat. Nos. 3,093,200; 3,172,490; and 3,367,432 are illustrative of this tact taken by the art and which need but not be employed by Applicant, since his technique overcomes this effect without the necessity for decoupling.
Ancillary to the problem of weighing the railroad cars, has been the problem of identifying the cars. Therefore, one facet of the art employs certain codes on the railroad cars in conjunction with a scanner system, which can identify the car and couple each car's identification with its registered weight. The scanning system technology is illustrated by U.S. Pat. Nos. 3,106,706 and 3,393,757 and plays no part in Applicant's invention, although it can be used as a useful adjunct to the system of Applicant's invention.
The art has also been concerned about the design of weigh bridges. In general, these are steel platforms in which tracks are mounted so that cars can pass over them wthout any interruption. They are installed with strain gauges, a form of transducer which generates an electrical signal directly proportional to the weight of the load. Examples of weigh bridge designs are U.S. Pat. Nos. 3,421,593 and 4,061,198.
From an early stage in the development of the art, great efforts have been made to develop systems in which accurate weighings could be obtained without stopping each individual car for weighing. Thus, the concept and goal of in-motion weighing was a desideratum of the industry. These are sometimes referred to as dynamic weighing systems.
They generally followed two main streams of development. One of these is in which switches were used, usually mechanical switches in which the wheels of the vehicle would actuate various electronic circuits. Various logic systems were employed to detect and count axles, subtract and add various weight combinations which are generated by the axles, etc. U.S. patents illustrative of this approach include U.S. Pat. Nos. 3,605,801; 3,403,740; 3,192,535; 3,556,236; 3,646,327; 3,646,328 4,134,464; and 3,374,844.
Another variant was the dynamic system in which no switches were employed and the technique was to utilize a plurality of transducers to detect the weight spaced along the length of the weigh scale so that the transducers would produce a continuously varying signal as a load passed over them. Examples of patents covering this technology are: U.S. Pat. Nos. 3,674,097; 3,063,633; 3,276,525; 3,439,524; 3,446,298; 3,406,771; 3,101,800; and 4,094,367.
Miscellaneous other relevant techniques are described in U.S. Pat. No. 3,512,004 which utilizes radiation positioning to control the movement of cars to a predetermined position. U.S. Pat. No. 3,842,922, which totalizes all individual axle weights on a given scale, U.S. Pat. No. 3,721,820 uses heat sensors to detect hot boxes. U.S. Pat. No. 3,750,158 teaches a fairly straightforward technique of a photo sensor to determine when a person has entered a room with a scale in it and a photo sensor, to close the door behind, forces that person to stay in the room long enough to have his or her weight recorded and then determine whether or not that person's weight has changed from the time the room has been entered. The objective in this patent is to ascertain whether or not the person has picked up any object in the room. Thus, it is a security device and is not related at all to the problem of weighing railroad cars in motion.